Organic electroluminescent diode (OLED), also known as organic light emitting diode, emits light based on the following principle: current is applied to certain organic material which can convert electric energy into luminous energy so as to emit light. Organic light emitting diode has the characteristics of active light emitting, high contrast, and low power consumption and the like, and has been widely used in the field of new generation flat panel display.
The flat panel display apparatus using organic light emitting diode will produce heat in usage. With the extended period of usage, heat might accumulate in the device of the display apparatus due to slow thermal conduction. If the temperature of the device exceeds the tolerable temperature of the organic light emitting diode material, it might cause vaporization, deterioration or other harmful phenomenon to the material of the organic light emitting diode, thereby affecting the usage life of the flat panel display apparatus. However, the current packaging structures of the organic light emitting display devices mostly employ cover plate type package, that is, a method in which, the cover plate is first bonded to the substrate of the organic light emitting diode by using packaging adhesive, then the packaging adhesive is cured. The main material of currently used packaging adhesive is epoxy resin, with a thermal conductivity of 0.2 W(m·K)(watt/meter/Kelvin). And the thermal conductivity of the glass cover plate is about 0.75 W(m·K)(watt/meter/Kelvin). Both of the materials have small thermal conductivities, poor thermal conduction performance, resulting in slow internal thermal conduction in the organic emitting diode, which is disadvantageous to the long term usage of the organic light emitting display device.
Moreover, in the current packaging structure of the organic light emitting display device, by employing the method of adding desiccant, the damage to the organic light emitting display device caused by water vapor can be effectively avoided. However, in existing packaging method, desiccant is often dispersed in the packaging adhesive, or can be embedded in the packaging adhesive at the edge position in bulk form. However, in the two methods, the usage of lots of desiccants might degrade the adhesion between the packaging adhesive and the cover plate, the organic light emitting diode, and the substrate, thereby influence the package effect.
Carbon nanotube is a kind of material with high thermal conductivity (thermal conductivity 3180-3500 W/(m·K)), whose radial thermal expansion is almost zero, resulting in better thermal conductive effect than metal (pure copper thermal conductivity 401 W/(m·K), pure aluminum thermal conductivity 237 W/(m·K)). The thermal conduction performances of carbon nanotube composite material and carbon nanotube doped material are also widely researched to optimize the performance of carbon nanotube. Carbon nanotubes can be classified in to two types based on their structure: single-walled and multi-walled. Among them, the single-walled structure can be classified into three types based on the curved conformation of the graphite sheet: armchair, Zigzag and chiral. As to chiral different carbon tubes, doping, absorbance and vacancy defects can influence the thermal conduction function, wherein the armchair carbon tube is most sensitive to doping defects, causing its coefficient of thermal conductivity to decrease dramatically. The screening and optimizing of the carbon nanotube is very important. Research results show that uniform modification or fill to carbon nanotube can effectively preserve or even improve the thermal conduction performance of the carbon nanotube. Therefore, modifying or filling carbon nanotube with other nanometer material can impart the carbon nanotube material other properties while persevering high thermal conductivity. Moreover, the carbon nanotube has large resistance, and can become insulator after processing, which when contacts conductors such as metal, can transfer heat from charged metal without transferring electricity.
Therefore, it is quite necessary to provide an organic light emitting display device with a good packaging effect, good tightness and good heat dissipation performance as well as its packaging method.